This is a really great and fun tower defense game mixed with real-time action game... once you get the hang of it. Not to imply that it isn't fun right out of the gate, but it doesn't take very long for you to sort of realize that the game wants to be played in a very particular way, and if you aren't picking up the game's hints, it can get frustrating. There are frankly a lot of things about this game that are VERY USEFUL INFORMATION that it doesn't do a particularly good job of explaining to you. Here are just a few examples of things that are confusing and will drive players to consult ye olde Google:
1. How in the hell does the skull system work...???
2. I'm kicking a** and no orcs are getting into the rift, but I keep getting low scores...???
3. I have no idea what I'm supposed to do with this steam trap...???
Here are the short versions to those answers:
1. For 5 skulls, beat the level, get lots of combos, don't lose any rift points, and beat the mysterious "target time" that you have no idea exists or what the specific target time is unless you finish the level and select "statistics" from the end-of-level options then look for the fine print.
2. Combos. It's not enough to just kill all the orcs and keep them away from the rift. You have to kill lots of orcs simultaneously, really fast, as much as possible.
3. The steam trap is a worthless piece of crap that does nothing useful (and it's not the only one). Just ignore it.
If you want to head down the path of victory instead of the path of what-the-hell-is-going-on, then here is where you should start:
1. Wind Bracers
3. Tar pits
6. Ice amulet
7. Steel Weaver -> Death Augmenter
You'll unlock these as you progress, but those are probably the most useful traps in the game. Orcs plodding slowly through a snaking trail of tar while 15 archers fire flaming arrows at them simultaneously? While you simultaneously use the bracers to blow huge crowds of them into a lava/acid pit? Victory.
You'll pick up more tricks and variations as you go. Swinging mace trap + tar pits = virtually unstoppable. Expensive, but heavenly.
Are fliers a problem? Or maybe ogres? Or maybe hunters? ICE AMULET THOSE A-HOLES.
It's really fun once you get the feel for it and find the optimal strategies, but aspects of the game can definitely feel mysterious and frustrating at first.
I'm just three levels away from 5-skulling the entire game. It's been a good time.